Image forming apparatus

ABSTRACT

An image forming apparatus has an actuation portion emitting an actuation sound and an internal part provided away from and opposed to the actuation portion. Further the image forming apparatus has a sound absorbing member formed of a foam metal, and provided away from the internal part between the actuation portion and the internal part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus such as acopy machine and an LBP (laser beam printer), particularly an imageforming apparatus to attenuate echo of actuation sound of an actuationportion of the apparatus.

2. Description of the Related Art

Conventionally, as a countermeasure against noise of the image formingapparatus, it has been considered how to reduce the actuation sound,with regard to the actuation portion (sound source) such as motor,solenoid, and roller, which emits the actuation sound or noise. And ithas been considered how to muffle the noise by sealing the actuationportion (Japanese Patent Application Laid-Open No. 2002-307780). Furtherit has been considered to provide the sound absorbing material near theactuation portion (Japanese Patent Application Laid-Open No. H03-2063).

However, the actuation portion of the image forming apparatus includes amanual sheet feed portion, a movable tray of a sheet discharge portion,and so on, which are disposed outside the housing of the image formingapparatus and are not sealed completely. With regard to the actuationsound of these actuation portions transmits to a person with aggregatesum of the sound directly emitted from an unsealed opening and the soundreflected from exterior walls around the actuation portion and emittedfrom the opening. There is a structure of applying a small amount ofsound absorbing member on the exterior wall to attenuate the reflectedsound. As the sound absorbing member, porous members such aspolyurethane foam and inorganic fiber such as glass wool have beenwidely employed.

An aluminum has been employed to absorb sound (Japanese PatentApplication Laid-Open No. 2002-244403). Foam metal also has beenemployed to absorb sound (Japanese Patent Publication No. H05-9036).

However, the conventional image forming apparatus has had a problem oflittle effect of absorbing reflected sound. That is, the centerfrequency of the actuation sound of the actuation portion which isdifficult to seal is mainly not more than 1 kHz, while the soundabsorbing members of porous members such as polyurethane or inorganicfiber sound absorbing members are effective against a frequency band ofnot less than 1 kHz. Therefore, the conventional reflected soundattenuation mechanism has not been suitable for low frequency.

Further, for example, in the case that a sound absorption degree of notless than 0.8 at a noise center frequency of 500 Hz is achieved, athickness of the sound absorbing member is required to range from about50 mm to about 100 mm. For this reason, in the conventional apparatus,it has been difficult to employ the sound absorbing member for the imageforming apparatus, because it requires a large space for applying themember. If the sound absorbing member is used, this poses the problem ofmaking the image forming apparatus lager in size.

Although the above explanation is related to the problem with theactuation portion disposed outside the housing, there has been also thesame problem with the actuation portion disposed inside the housing andopposed to an opening portion of the housing. That is, there has been aproblem in which the actuation sound of the actuation portion isreflected by the internal part of the housing to leak as noise from theopening portion of the housing to outside.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image formingapparatus to enhance effect of reducing reflected actuation sound of anactuation portion.

The image forming apparatus of the present invention includes: aninternal part away from a wall of a housing inward of the apparatus; andan actuation portion emitting an actuation sound and provided outsidethe housing, wherein an opening portion is provided in the wall betweenthe internal part and the actuation portion and a sound absorbing memberformed of foam metal is provided in the opening portion.

Also, an image forming apparatus of the present invention includes: anactuation portion emitting an actuation sound and disposed, in ahousing, opposite to an opening formed in a wall of the housing; aninternal part disposed, in an inner part of the housing, opposite to theactuation portion and away from the actuation portion; and a soundabsorbing member formed of foam metal, provided between the actuationportion and the internal part and away from the internal part.

Also, an image forming apparatus of the present invention includes: anactuation portion emitting an actuation sound; an internal part disposedopposite to the actuation portion and away from the actuation portion,wherein the internal part is a part constituting an image formingportion to form an image on a sheet; and a sound absorbing member formedof foam metal, provided between the actuation portion and the internalpart and away from the internal part.

In the image forming apparatus of the present invention, a space isformed between the sound absorbing member made of foam metal and theinternal part. Therefore, the actuation sound of the actuation portioncan be attenuated not only by the foam metal but also the space.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an enlarged view showing a reflected sound reduction structurein an image forming apparatus according to an embodiment of the presentinvention.

FIG. 2 is a right side view of FIG. 1.

FIG. 3 is an illustration explaining the reflected sound reductionstructure in the case of propagating sound waves in a direction of platethickness of a foam metal plate.

FIG. 4 is a graph comparing sound absorption performances of the foammetal plates and those of the other sound absorbing members.

FIG. 5 is a schematic block diagram explaining the sound absorptionprinciple of the foam metal plate.

FIG. 6 is a front sectional view showing a schematic construction of theimage forming apparatus according to the embodiment of the presentinvention.

FIG. 7 is an enlarged view of other reflected sound reduction structureprovided in the image forming apparatus according to the embodiment ofthe present invention.

FIG. 8 is a graph showing a relation between the space behind the foammetal plate and the sound absorption degree.

FIG. 9 is a graph showing the sound absorption performances of the otherfoam metal plates.

DESCRIPTION OF THE EMBODIMENTS

An image forming apparatus of an embodiment of the present inventionwill be described hereinafter with reference to the drawings. Numericalvalues employed in the embodiments of the present invention arereference values and do not necessarily limit the present invention.

FIG. 6 is a cross-sectional front view showing a schematic constructionof the image forming apparatus according to the embodiment of thepresent invention.

In the image forming apparatus 20, an image of an original is read by animage reading portion 8, an electrostatic latent image is formed on asurface of a photosensitive drum 1 as a latent image bearing member byan exposure from an image writing portion 9 in accordance with a commandfrom a controller (now shown) based on the read image data. The surfaceof the photosensitive drum 1 is uniformly charged to a predeterminedpotential before the exposure by a charger 2. An electrostatic latentimage is formed on the photosensitive drum 1 by a laser beam or the likeirradiated on the uniformly charged surface of the photosensitive drum 1from the image writing portion 9. The electrostatic latent image formedon the photosensitive drum 1 is toner-developed with toner as adeveloper by a developing device 3 to form a toner image. And then thedeveloped toner image is conveyed to a portion opposed to a transferdevice 4 by the rotation of the photosensitive drum 1.

In accordance with the conveyance of the developed toner image, a pickuproller 51 of a manual sheet feed unit 5 feeds a sheet S as a recordingmedium one-by-one from a sheet tray 25. The sheet is timely conveyed tobetween the photosensitive drum 1 and the transfer device 4 by a pair ofregistration rollers 6. And while the sheet S is passing through betweenthe photosensitive drum 1 and the transfer device 4, the transfer device4 transfers the toner image on the photosensitive drum 1 to the sheet S.The sheet is also fed from a cassette 13 so that the toner image istransferred on the sheet.

The sheet S on which the toner image is transferred is conveyed to afixing device 7 by a conveying device 12. The fixing device 7 nips thesheet while heating the sheet. The fixing device 7 is heated by a heater(not shown) provided in a fixing roller of the fixing device 7 to fusethe toner image on the sheet S to fix the toner image to the sheet S.And then, the sheet S on which the toner image is fixed is discharged toa tray 11 outside a housing 21 by a pair of discharging rollers 10. Inthis way, a series of the image forming processes in the image formingapparatus is completed.

Next, a reflected sound reduction structure will be described withreference to FIGS. 1 and 2.

FIG. 1 is an enlarged view of the reflected sound reduction structure 24in FIG. 6. The manual sheet feed unit 5 constitutes a part of anexterior wall 22 of the housing 21. The manual sheet feed unit 5comprises a pickup roller 51, a pickup support plate 52 rotatablyaxially supporting the pickup roller 51 to bring the pickup roller 51into and out of contact with the sheet S, a receptive stopper 53 todetermine a rising position of the pickup supporting plate 52. When thepickup support plate 52 is raised, the pickup roller 51 is separatedfrom the sheet S. A manual sheet feed cover 54 of the sheet feed unit 5and the receptive stopper 53 are integrally formed with ABS resinmaterial and applied with coating for an exterior part.

FIG. 2 is a right side view of FIG. 1. An opening portion 57 is formedin the center of the exterior wall of the manual sheet feed cover 54near the receptive stopper 53. The opening portion 57 is provided with afoam metal plate 55 having air-permeability porous member so as to closethe opening portion 57. The foam metal plate 55 as a sound absorptionmaterial is also applied with coating for an exterior part. The foammetal plate 55 is fixed to the manual sheet feed cover 54 with screws 56at both lateral ends which are boring processed. Between a foam metalplate 55 and a reflection wall 3 a opposed to the foam metal plate 55 ofthe developing device 3, a below-mentioned predetermined distance isspaced to form a space 69. This space 69 is a space for attenuatingsound. A sheet supply port 26 supplying sheets stacked in the manualsheet feed tray 25 is formed below the foam metal plate 55.

With the above configuration, when the pickup support plate 52 is raisedby a solenoid 98, the pickup support plate 52 is brought into contactwith a surface of receptive stopper 53 to produce collision noise. Thepickup roller 51, the pickup support plate 52, and the receptive stopper53 are an actuation portion emitting actuation sound.

The collision noise is radially propagated in air. When there is a wallnear the pickup support plate 52 and the receptive stopper 53 as a soundsource, the collision noise is reflected by the wall so that a soundpressure in an open space opposed to the wall surface is increased. Thefoam metal plate 55 is located on the left side of the pickup supportplate 52 and the receptive stopper 53. This foam metal plate 55dramatically reduces the reflected sound. Especially, when a lineconnecting the opening portion 57 and the actuation portion as a soundsource is perpendicular to one side surface (the reflection surface 3 ain this case) of the developing device 3, there is a strong possibilitythat the sound from the actuation portion is reflected by the reflectionsurface 3 a to leak from the opening portion. However, in the embodimentof the present invention, since the foam metal plate 55 is locatedbetween the actuation portion and developing device 3, the reflectedsound is reduced by the sound absorption effect of the foam metal plate55.

Here, a sound absorption mechanism of the foam metal plate 55 will bedescribed. FIG. 3 shows a reflected sound reduction structure 44 whenthe sound waves are propagated in a direction of plate thickness of thefoam metal plate 55. Cells 62 independently formed (black portion inFIG. 3) are communicated with each other by through-holes 64 formed byextending through the foam metal plate 55. The sound waves 66 arediffusely reflected by a metal shell 63 of the cell 62 exposed on thesurface to be interference-attenuated by reflected waves. And a part ofthe sound waves 66 passes through the thorough-holes 64. The passedsound waves are expanded and attenuated within a next cell 62, andlikewise, the sound waves are repeatedly expanded and attenuated everytime the sound waves move to an adjacent cell. And when the sound wavesarrive at the opposite side of the foam metal plate 55, the sound wavesare reflected by the reflection wall 3 a, which is a predetermineddistance away from the foam metal plate 55 through the space 69, to bemade into reflected waves 81, thereby the noise is reduced by theinterference, expansion, and friction with the metal shells (cell wallsurfaces) 63.

FIG. 4 is a graph showing a comparison of sound absorption performancebetween the foam metal plates 55 and other sound absorbing members. InFIG. 4, absorption members in the graph represented by reference signs(a), (b), and (c) are foam metal A having a plate thickness of 10 mm. Asound absorbing member represented by a sign (d) is a glass wool (platethickness: 25 mm). A sound absorbing member represented by a sign (e) isa urethane (plate thickness: 15 mm).

The foam metal A is formed of aluminum, which is an air permeabilityporous member which is cut after closed cell molding, and subjected to acompression process. The cracks are caused by compressing the aluminumwith which the closed cells are formed, so that the closed cells arecommunicated with each other through the cracks. And the space 69 shownin FIG. 3 is provided at the back of the sound absorbing memberrepresented by (a), (b), and (c) in the graph. A distance of the space69 is 30 mm for the absorption member represented by the sign (a), 60 mmfor (b), and 90 mm for (c).

As shown in FIG. 4, in order to absorb a sound of a relatively lowfrequency not more than 1 kHz, the foam metal plate of theair-permeability porous member is used as a sound absorbing member and aspace is provided at the back of the foam metal plate, thereby soundabsorption degree is remarkably increases compared with that of theconventional sound absorbing member.

FIG. 5 is a schematic block diagram of the reflected sound reductionstructure. A collision sound repeats the expansion attenuation and theinterference attenuation due to the diffuse reflection in the process ofpassing through the foam metal plate 55 to reach the opposite side ofthe foam metal plate 55. On the opposite side of the foam metal plate55, the developing device 3 (See FIG. 1.) is arranged as internal partnecessary for the image forming process. Between the foam metal plate 55and the reflection wall 3 a of the developing device 3 disposed in alocation opposed to the foam metal plate 55, a space having a width W(e.g. 20 mm) is provided. Traveling waves having passed through the foammetal plate 55 are reflected by the reflection wall 3 a and propagatedto and from in the space 69 of 20 mm. In this process, the travelingwaves and reflected waves perform interference attenuation. Theattenuated reflected sound again passes through the foam metal plate 55.Therefore, about 80° of the actuation sound (incident sound) emittedfrom the sound source is absorbed when the sound returns to the soundsource side.

In this embodiment, the foam metal plate 55 is arranged in a part of themanual sheet feed cover 54, which is an exterior wall of the manualsheet feed unit 5. The foam metal plate 55 is easy-machinable inmachining such as bending and boring. For this reason, the manual sheetfeed cover 54 may be entirely formed with foam metal.

Further, the example of using foam metal for the exterior wall is notlimited to the manual sheet feed unit, but foam metal can be applied toa portion, where the actuation portion which emits an actuation sound ofa relatively low frequency is disposed in an open space, for example, ofan exterior cover near the movable tray in a sheet discharging portionto which a sheet is discharged.

Furthermore, in this embodiment, a surface corresponding to thereflection wall is the reflection wall 3 a of the developing device 3.The reflection wall, however, may be a surface of another internal partin the image forming apparatus. And in the case that there is a spacebetween the exterior wall of the housing and the internal part and thereis a noise source having an open space outside the exterior wall of theapparatus, the similar effect is obtained.

In addition, as shown in FIG. 7, the present invention is alsoapplicable for attenuating an actuation sound generated by a pair ofsheet conveying rollers 41 as an actuation portion inside the housing 21opposed to the sheet discharging port 27 as an opening portion formed inthe exterior wall 22 of the housing 21.

That is, between a pair of sheet conveying rollers 41 and a reflectionwall 7 a of the fixing device 7 as an internal part, a foam metal plate71 as a sound absorbing member is disposed away from the reflection wall7 a to form a space 72 between the foam metal plate 71 and thereflection wall 7 a. With this reflected sound reduction structure 28,the actuation sound of the pair of sheet conveying rollers 41 isattenuated by the foam metal plate 71 and the space 72 and cannot beamplified by the reflection due to the reflection wall 7 a.

Next, a preferable example of applicable scope of each feature in thepresent invention will be described hereinafter.

1. Regarding Porosity of Foam Metal

With regard to the sound absorption performance of the foam mental, ahigh porosity is generally preferable. And a material of the soundabsorbing member of the foam metal produced by the typical manufacturingmethod is mainly aluminum (A cast metal may be used.). When the materialof the foam metal is aluminum and the porosity is about 50%, an aluminumspecific gravity becomes 2.74 gf/cc, and an apparent specific gravity is1.37 gf/cc, which is substantially equivalent to a gravity of 1.3 gf/cc.of ABS used as general resin material for an exterior coating.

That means, porosity of not less than 50% is preferable to theconventional performance, not only from a viewpoint of the soundabsorption performance but also from an ergonomic viewpoint such as anoperability of opening and closing of the manual sheet feed unit, and aphysical distribution or an installation cost because of reduction inweight of the body of the apparatus. The present embodiment uses a foammetal of aluminum having porosity not less than 50° and not more than95°.

2. Regarding Width (thickness) of Space

When the width of the space 69, 72 behind the foam metal plate 55, 71increases, a degree of sound absorption at a low frequency bandwidth isimproved. However, a clearance between the foam metal plate and aninternal part (the inner parts in the body of an apparatus) cannot beset without limit. FIG. 8 is a graph showing a relation between a spacebehind the foam metal plate and a degree of sound absorption. In FIG. 8,sound absorbing members represented by reference signs (f), (g), (h),and (j) are foam metal plates B having a plate thickness of 10 mm.Incidentally, the foam metal plate B has the same thickness of 10 mm asthe foam metal plate A, but an expansion ratio of the foam metal plate Bis higher than that of the foam metal plate A.

Material of the foam metal plate B is aluminum. The foam metal plate Bis air-permeability porous member which is cut after closed cellforming, and through-holes are formed. The closed cells are communicatedwith each other by forming the through-holes in the aluminum with whichthe closed cells are formed. With regard to a width of the space behindthe foam metal plate B, a graph shown by the sign (f) is 0 mm, a graphshown by the sign (g) is 20 mm, a graph shown by the sign (h) is 40 mm,and a graph shown by the sign (j) is 60 mm.

In FIG. 8, for the foam metal plate of graph (f) with no space, degreeof sound absorption is 0.8 at a frequency of 2.5 kHz, and the degree ofsound absorption not less than 0.8 cannot be achieved within a range offrequencies not more than 1 kHz. However, for the foam metal platehaving the space width of 20 mm shown by the sign (g), degree of soundabsorption is 0.8 at a frequency of 1 kHz. Therefore, the actuationsound can be attenuated, if the space width is set to not less than 20mm. And in the image forming apparatus of the present embodiment, it isrealistically possible that an internal part is installed to allow anopening to be spaced about 20 mm away from the interior surface of theexterior wall 22. And effective reflected sound reduction structure canbe arranged in the conventional space.

In the applicable places which have affordable space inside the body, itis theoretically preferable that a thickness of space 69, 72 is set to(¼) λ where a wavelength at which a sound of a center frequency of noiseis propagated in the air is λ, because the maximum interference canceleffect is achieved.

3. Plate Thickness of Foam Metal

A plate thickness of the foam metal is not specifically limited forconvenience of a method of forming a foam metal plate 55, 71 and from aviewpoint of sound absorption performance. FIG. 9 is graphs showing thesound absorption performances of foam metal plates different from thesound absorbing member mentioned above in the embodiment. In FIG. 9,sound absorbing members of graphs represented by the signs (k) and (m)are a foam metal C having a plate thickness of 2.5 mm. A width of thespace behind the foam metal C is 50 mm for the graph of the sign (k) and100 mm for the graph of the sign (m). Although the plate thickness ofthe foam metal plate in FIGS. 4 and 8 used in the explanation of theembodiment is 10 mm, it is apparent for FIG. 9 that a sound absorptiondegree not less than 0.8 can be accomplished at a frequency of 1 kHz orless depending on the behind space, even with the plate thickness of 2.5mm. And generally a plate thickness of resin material used for exteriorwalls of the image forming apparatus is ranging from about 2.5 mm toabout 3 mm, and it is possible to replace with the conventional exteriorwalls in a viewpoint of the plate thickness.

That is, plate thickness of the optimal sound absorption effect may beselected within the scope where there is no change in a position of anexterior wall and there is no intrusion into an internal part space inthe housing.

With the above mentioned configuration, the foam metal plate as a soundabsorbing member is excellent in heat resistance to maintain for examplea sound absorption degree of not less than 0.8 at a center frequency of500 Hz, thereby products can obtain the standard of flame retardancy. (Aflame retardancy for a sheet material as an exterior is not less thanthe standard HF-2 and not more than 25 cm²).

The conventional sound absorbing member made of inorganic fiber such asglass wool cannot be self-support as a single unit because of its lowmechanical strength, therefore it is difficult to install on theexterior wall without forming a complex structure together with aperforated metal plate or a resin plate. While, the sound absorbingmember of the foam metal plate of the present invention has a highmechanical strength and it is easy to install.

The conventional sound absorbing member such as polyurethane foam andglass wool has troubles of easy breakage damage and breakage into dustdue to vibration, and occasional time degradation. Further, theperformance of sound absorption may become low when absorbing water inthe atmosphere. While, the sound absorbing member of the foam metalplate of the present invention has less possibility of breakage damageand time degradation. Further, the sound absorption performance ishardly reduced even though it absorbs water in the atmosphere, and itcan maintain the sound absorption performance for a long time.

The conventional sound absorbing member can not be coated with coating,thereby it is not suitable for an exterior member while the soundabsorbing member of foam metal plate of the present invention can becoated with coating and can be used as an exterior member.

If the conventional sound absorbing member is made self-supported byforming a space between it and the reflection wall, it is required tosupport the conventional sound absorbing member by fastening through aspacer to the exterior wall or to support the exterior wall and thesound absorbing member by a duct structure. Therefore, it is impracticalin terms of cost, space, and exterior appearance. On the contrary, sincethe sound absorbing member of the foam metal plate of the presentinvention is superior in strength to the conventional sound absorbingmember, installation structure becomes simple. Therefore, the imageforming apparatus of the present invention can be made the practicalstructure in terms of cost, space, and exterior appearance.

The reflected sound reduction structure for the actuation portion (soundsource), which cannot be sealed, emitting the actuation sound in theimage forming apparatus of the present invention is provided with thesound absorbing member formed of a foam metal plate in the openingportion formed in the exterior wall as a reflection wall. Therefore, aspace for attaching the sound absorbing member between the sound sourceand the exterior wall is dispensable. As a result, the image formingapparatus can be prevented from made into larger in size.

As the image forming apparatus according to the invention is providedwith a space on the backside of the sound absorbing member to increasethe degree of sound absorption, the space between the exterior wall andthe internal part in the apparatus can be effectively used so as toavoid an increase in size of the image forming apparatus.

In the image forming apparatus of the present invention, the foam metalplate can dramatically reduce the low frequency noise, which is a soundof mainly not more than 1 kHz emitted from a sound source, which cannotbe sealed in the vicinity of the exterior, and which noise is difficultto reduce by the conventional method of attaching the sound absorbingmember on the exterior wall.

If the present invention is applied to the image forming apparatus, asshown in FIG. 7, in which the actuation portion opposed to the openingportion formed in the exterior wall of the housing is provided insidethe housing, the apparatus can improve the attenuation effect. Furtherit can efficiently utilize the space between the actuation portion andthe reflection wall of the internal part, thereby avoiding an increasein size of the apparatus.

Further, in the image forming apparatus as shown in FIG. 7, not only thefoam metal but also the space between the internal part and the foammetal contributes the actuation sound reduction, thereby increasing theactuation sound attenuation effect to decrease the actuation sound ofthe actuation portion, which is leaked from the opening portion. Inaddition, even if the actuation sound is not more than 1 kHz, theactuation sound can be surely attenuated.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2005-349847, filed Dec. 2, 2005, which is hereby incorporated byreference herein in its entirety.

1. An image forming apparatus comprising: an internal part away from awall of a housing inward of the apparatus; an actuation portion emittingan actuation sound and provided outside said housing; and a soundabsorbing member formed of a foam metal and provided in an openingportion, which is provided in said wall between said internal part andsaid actuation portion.
 2. An image forming apparatus according to claim1, wherein a porosity of said foam metal is 50% or more.
 3. An imageforming apparatus according to claim 1, wherein a space between saidinternal part and said sound absorbing member is set to substantiallyone fourth of a wavelength of the actuation sound.
 4. An image formingapparatus according to claim 1, wherein said sound absorbing member isformed of aluminum.
 5. An image forming apparatus according to claim 1,wherein a space between said internal part and said sound absorbingmember is set to 20 mm.
 6. An image forming apparatus according to claim1, wherein said actuation portion comprises a pickup roller lifting andlowering to feed a sheet supported on a tray and said internal part is acomponent constituting the image forming apparatus for forming an imageon a sheet.
 7. An image forming apparatus comprising: an actuationportion emitting an actuation sound, provided inside a housing andopposed to an opening portion formed in a wall of said housing; aninternal part provided in an inner part of said housing, opposed to andaway from said actuation portion; and a sound absorbing member formed ofa foam metal, provided between said actuation portion and said internalpart, and away from said internal part.
 8. An image forming apparatusaccording to claim 7, wherein a porosity of said foam metal is 50% ormore.
 9. An image forming apparatus according to claim 7, wherein aspace between said internal part and said sound absorbing member is setto substantially one fourth of a wavelength of the actuation sound. 10.An image forming apparatus according to claim 7, wherein said soundabsorbing member is formed of aluminum.
 11. An image forming apparatusaccording to claim 7, wherein a space between said internal part andsaid sound absorbing member is set to 20 mm.
 12. An image formingapparatus comprising: an actuation portion emitting an actuation sound;an internal part provided away from and opposed to said actuationportion, wherein said internal part is a component constituting an imageforming portion for forming an image on a sheet; and a sound absorbingmember formed of a foam metal, provided between said actuation portionand said internal part, and away from said internal part.